Electrical contact device



p 7, 1954 I. v. RlGBY 2,688,665

ELECTRICAL CONTACT DEVICE] Filed Feb. 21, 1952 Inventor IVOR Vlvm v P/wy rm-A Ha Attorney which engages the contact blade 3.

Patented Sept. 7, 1954 ELECTRICAL CONTACT DEVICE Ivor Vivian Rigby,

to The British Letchworth, England, assignor Tabulating Machine Company Limited, London, England, a British company Application February 21, 1952, Serial No. 272,849

Claims priority, application Great Britain November 26, 1951 Claims. 1

This invention relates to mechanically operated electrical contact devices.

The object of the invention is to provide an improved mechanically operated electrical con tact device particularly adapted for operation at high speed.

According to the invention a mechanically operated electrical contact device has movement of the non-driven contact blade in one direction limited by a non-resilient stop and in the other direction restrained'by a strip of resilient material.

The invention will now be described by way of example with reference to the accompanying drawing. 1

A right angle bracket 2 is secured to a mounting plate I. Two screws 5 pass through the upstanding part of the bracket. On these screws are held a brass terminal strip 6, a spring contact blade 3 in contact therewith, an insulating separator 8, a brass terminal strip I, a spring contact blade 4 in contact therewith, a strip of rubber I0, a second insulating spacer l3 and a clamping block 9. The contact blades and terminal strips are insulated from the screws by sleeves 23.

The strip of rubber It extends beyond the free end of the contact blade 4 and the free end of the strip is held between two L-shaped members II which are drawn together by a screw I2. The members I I are supported by screw I4 passing through a bracket I3 secured to the plate I. Two compression springs I5 separate the members II and the bracket I3, so that the tension of the strip I0 may be set by adjusting the screws I4. The position of the bracket I3 is such that the strip I0 is tensioned to press the contact blade 4 against the terminal strip I which extends part of the way along the contact blade.

Journalled in bearings in the plate I is an operating shaft It. A bushing I1 is mounted eccentrically on this shaft and keyed to it. The bushing is a tight push fit in the inner ring of a ball race H. The outer ring of the ball race is a tight push fit in a hole in a plate I9.

An extension of the plate I9 carries a pin 22 Formed in this extension is a slot 20 which engages a pin 2| fixed to the plate I.

Thus as the shaft I6 rotates, the plate I9 is reciprocated by the eccentric bushing ll. The pin 22 moves the contact blade 3 towards the blade 4 and when the contacts make continues to move both blades downwards. The plate then begins to move upwards and the contact blades follow until movement of the blade '4 is limited by the terminal strip 4. The blade 3 continues to move upward, so breaking the contact, under its own spring tension, until it reaches approximately the position shown in the drawing. In this way, the contacts are made once during each revolution of the shaft IS.

The rubber strip Ill is always in contact with the blade 4 and so damps out any tendency for the blade to bounce when it is contacted by the blade 3 and when it is restrained by the strip 7, thus improving the operation at high speeds. The tension of the strip is adjusted to provide effective damping at the particular operating speed required, such as 10,000 operations per minute.

Furthermore, the present construction is an improvement over cam operated contacts in that the contact blade 3 is not subjected to wear by frictional engagements with a cam surface, nor is it subjected to shocks since the blade is alway maintained in contact with the pin 22 by the spring tension of the blade.

What I claim is:

1. An electrical contact device comprising first and second springy contact blades, one end of each being fixed and the other ends being normally spaced but being mutually engageable by bending of said second contact, a non-resilient fixed stop limiting movement of said first blade towards said second blade, a strip of resilient material in tension anchored at one end and attached to said first blade, said strip restraining movement of said first blade in the direction away from said second blade although permitting movement of said first blade away from said stop under restraint, and mechanical means for positively driving said second blade towards said first blade through a distance causing said second blade to contact said first blade and thereafter said first blade to move away from said stop against the resilient restraint of said strip.

2. An electrical contact device comprising first and second springy contact blades, one end of each being fixed and the other ends being normally spaced but being mutually engageable by bending of said second contact, a non-resilient fixed stop limiting movement of said first blade towards said second blade, a strip of resilient material in tension anchored at one end and attached to said first blade, said strip restraining movement of said first blade in the direction away from said second blade although permitting movement of said first blade away from said stop under restraint, and cyclically operating means for alternately positively driving and 3. An electrical contact device comprising first and second light springy contact blades, one end of each being fixed and the other ends being normally spaced but being mutually engageable by bending of said second contact, a non-resilient fixed stop normally engaged by said first member and limiting movement of said first blade towards said second blade, a strip of resilient material in tension anchored at one end and attached to said first blade, said strip permitting movement of said first blade away from said stop against the restraint exerted thereby, means for adjusting the tension in said strip, and mechanical means for positively driving said second blade towards said first blade through a distance causing said second blade to contact said first blade and thereafter said first blade to move away from said stop against said restraint.

4. An electrical contact device comprising first and second light springy contact blades, one end of each being fixed and the other ends being normally spaced but being mutually engageable by bending of said second contact, a non-resilient fixed stop limiting movement of said first blade towards said second blade, a strip of resilient material in tension attached to said first blade, said strip restraining movement of said first blade in a direction away from said stop, a rotary driving shaft, a bushing secured to said shaft, a ball race mounted on said bushing, a reciprocating member mounted on said ball race, means for limiting the movement of said member to reciprocation, and means mounted on said member for positively driving said second blade into contact with said first blade and thereby moving said first blade away from said stop against the action of said resilient strip.

5. An electrical contact device comprising first and. second light springy contact blades, one end of each being fixed and the other ends being normally spaced. but being mutually engageable by bending of said second contact, a non-resilient fixed stop limiting movement of said first blade towards said second blade, resilient stop means attached to said first blade and restraining movement of said first blade in a direction away from said stop, a rotary driving shaft, a bushing secured to said shaft, a ball race mounted on said bushing, a reciprocating member mounted on said ball race, means for limiting the movement of said member to reciprocation, and means mounted on said member for positively driving said second blade into contact with said first blade and thereby moving said first blade away from said stop against the action of said resilient stop means.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date.

1,047,260 Manson Dec. 17, 1912 1,426,873 Hunt Aug. 22, 1922 1,555,528 Tauber Sept. 29, 1925 1,861,641 Nicholson et a1. June 7, 2,341,390 Scott Feb. 8,, 1944 

